olemus
vektor, mis kuulub mingisse võre baasi või mooduli baasi
= a vector that belongs to some lattice basis or module basis

ülevaateid
https://en.wikipedia.org/wiki/Basis_(linear_algebra)
https://people.revoledu.com/kardi/tutorial/LinearAlgebra/BasisVector.html
https://math.stackexchange.com/questions/2341335/relation-between-basis-vectors-and-unit-vectors